As one example of the reserve battery, the battery for the fuse which induces explosion must have a relatively high voltage over 3.0V in use, endure short time discharge having 10 kΩ of load over about 30 seconds, and have a very small diameter of a few mm and a very small weight according to the property of the fuse for the personal firearm. In addition, the battery includes a switch operated by a set back force of about 30,000 G. The rising time of the battery after the operation of the switch must be equal to or shorter than 1 msec.